Warp beam control for textile machines



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WARP BEAM con'mor. FOR TEXTILE MACHINES Filed March 17, 1961 3Sheets-Sheet 3 flgggerl. Comm/Q5 Ari-claws vs 3,076,615 WARP BEAMCQNTROL FOR TEXTILE MACHXNES Robert L. Connors, Tonawanda, N.Y.,assignor to Van Raalte Company, Inc, North 'lonawanda, NJY. Filed Mar.17, 1961, Ser. No. 96,572 8 Claims. (Cl. 242-455) This invention relatesto motion control means and particularly to combined tensioning and feedcontrol means for continuous strands or strips of material such as infeeding warp threads to a textile machine.

The principles of the present invention will be discussed herein as thesame may be embodied in driving and controlling the rotation of warpbeams or Warp spools of tricot knitting machines to control the tensionof the numerous warp threads passing from a warp beam or spool to theknitting mechanism, such threads being sometimes referred tocollectively as the yarn sheet. As will appear from the followingdiscussion of this particular adaptation of the principles of thepresent invention, the conditions under which warp thread feedingoperations are accomplished present peculiar control problems which maybe present to a greater or lesser extent in other textile machines andin other industrial filament, strand, strip or sheet feeding.

A primary consideration in warp knitting machines is the constantfeeding of yarn from the warp beam to the knitting mechanism at auniform speed and under constant tension despite the constantly changingbeam diameter, as the yarn unwinds therefrom; the intermittent anduneven manner in which the knitting mechanism takes up the yarn in theknitting cycle; and other factors which tend to vary the relative speedof the warp beam and the tension of the yarn passing to the knittingmechanism.

In knitting machines generally and in tricot warp knitting machinesparticularly the knitting elements pull the yarn from the warp in anintermittent and somewhat erratic fashion. Considering a single stitch,the knitting motion involves pulling the yarn from the warp in aboutlive or six intermittent increments during each stitch, and even theseincrements are not uniform so that the resultant oscillations are not ofuniform amplitude.

A tension bar normally bears yieldably against the yarn sheet as itpasses between the warp beam and the knitting mechanism and this tensionbar, or its equivalent, thus oscillates rapidly since the yarn comesfrom the warp beam at a substantially continuous rate and is thus consumed at the knitting mechanism by intermittent increments and at anirregular rate.

This oscillation, while it is of quite small amplitude, is ofconsiderable frequency since it is perhaps five or six times the rpm. ofthe knitting machine which varies from about 400 to 1,000 r.-p.m. sothat the tension bar may oscillate as fast as 6,000 times per minute. InSimplex machines there are two stitches per rotation of the cam shaft sothat this frequency is perhaps twelve times cam shaft speed in suchmachines. Under ordinary circumstances this oscillation or vibrationsubstantially complicates the problem of maintaining constant tensionand uniform feeding speed but the system of the present inventionutilizes the oscillation of the tension means to effect accurate speedcontrol of the warp beam or spool.

Among other things, the manner in which the tension means oscillation isemployed in the present system for controlling tension and producing auniform warp feed speed is such as to substantially eliminate huntingand overshooting in the control adjustment means, which is aparticularly vexatious problem in prior art warp beam speed controlarrangements.

In warp knitting even more than in most other textile producingprocesses, tension control is of prime importance. Variations in yarntension manifest themselves by Patented Feb. 5, 1963 variations in thekind and quality of cloth which is produced. These variations may appearas visible shade marks in the fabric and in any event manifestthemselves in variations in runner length. This latter characteristic iswell understood in the knitting industry and measures the number ofinches of yarn consumed in making a given number of stitches.

Variations in runner length are so prevalent under present conditions inthe knitting industry as to be accepted as a necessary evil. Theaccuracy and uniformity of yarn tension in employing the apparatus andmethods of the present invention are such that runner length may be heldso accurately as to require no attention from beginning to end of a warpbeam. Furthermore, this constancy may be held to at various tensionadjustments so that runner length may be initially selected by apredetermined tension adjustment and continuously uniform results willfollow automatically.

Besides producing fabric of better quality, the present invention avoidswastage due to production of imperfect fabric and effects substantialsavings in laborbecause of the considerable reduction in attentionrequired with knitting machines employing the present warp beam andension control. Also, maintenance costs are reduced which effectssavings in labor costs.

Several embodiments of the principles of the present invention areillustrated in the accompanying drawings and described in detail in thefollowing specification. However, it is to be understood that suchembodiments are set forth by way of example and to illustrate theprinciples of the invention. The spirit and scope of the invention isnot limited to the exemplary embodiments thus shown nor otherwise thanas defined in the appended claims.

In the drawings:

FIG. 1 is a fragmentary side elevational view of portrons of a tricotknitting machine, illustrating one form of the waip feed and tensioningregulating means of the present invention in somewhat schematic form;

FIG. 2 is a fragmentary view of a portion of the structure of FIG. 1 onan enlarged scale, illustrating the contact adjusting means thereof:

FIG. 3 is a diagrammatic view of a modified form of the electricalportion of the control means of the present invention; and

FIG. 4 is a diagrammatic view .of a further modified form of suchelectrical portion.

PEG. 1 illustrates an embodiment of the present inventionin a simplerudimentary form which is satisfactory Within certain limitations orunder certain conditions and aptly illustrates the basic principles ofthe invention. However, it is difficult and not entirely practical underall conditions to make and break circuits carrying large currents veryrapidly, and accordingly the systems illustrated in FIGS. 2 and 3 are hihly advantageous and may be successfully employed throughout a widelyvarying range of the various operating conditions and requirements.

eferring to FIG. 1, the numeral 10 designates a warp beam or warp spoolof a tricot knitting machine. It will be understood by those skilled inthe knitting machine art that two such warp beams are normally employedbut an illustration of the manner in which the control means of thepresent invention operates in conjunction with one such Warp beam willsufiice, it being understood that the entire tensioning and speedcontrol arrangement may be duplicated in connection with the other warpbeam. Actually certain power supply components may be common to two warpbeam control setups merely in the interests of economy andsimplification.

The warp beam ll) is mounted upon a warp shaft 5.1 which is mechanicallydriven at a variable rate from the knitting machine proper, as forinstance from the cam shaft 12 thereof. The latter carries a sprocket 13which is connected to a sprocket 14 on a countershaft 15 by a drivingchain 16. In FIG. 1 a variable speed transmission is designated 20 andits. input and output shafts are designated 21 and 22, respectively.

Output shaft 22 connects with a worm shaft 23 by means of a coupling 24and a worm 25 on worm shaft 23 drives a worm wheel 26 on warp shaft 11.Thus the Warp beam is rotated from and with the cam shaft of theknitting machine but at a variable ratio determined by the speed settingof variable transmission 20. The worm drive to the warp shaft isinherently irreversible so that rotative moments of the warp shaftcannot be transmitted to the driving means.

In passing from warp beam 10 .to knitting mechanism indicatedschematically at 30 in FIG. 1 the Warp threads or Warp sheet indicatedat 31 pass beneath a snub rod 32 and then over a tension rod 33. As isknown in the art, the knitting mechanism 30 draws yarn from the warpbeam intermittently and this intermittent pull of the knitting mechanismagainst the warp yarn applies an intermittent tension to the warp yarn.Tension rod 33 may be resiliently mounted in various ways to apply ayieldable resilient tensioning force against the warp threads. In theillustrated instance the tension rod 33 is carried at one end oflaterally spaced tension arms 35 which are fixed to a transverselyextending tension arm pivot shaft 36.

The tension arms 35 are biased in a warp thread tensioning direction bycompression coil springs 37 which act between extensions 38 of thetension arms and adjustable abutment means 39 on spring rods 40. Asindicated above the tension arms 35 and pivot shaft 36 oscillate underthe periodic intermittent yarn pulling action of the knitting mechanism.If the mean position of the arms and shaft can be maintained constantwith a given, tension setting of abutment means 39, then uniform warptension is. assured and this in turn reflects a warp beam drive which isdelivering yarn at a speed synchronized with the speed of the knittingmechanism so that warp tension is rendered constant.

In the embodiment of FIG. 1 this synchronization and uniform tension areattained in the following manner. A contact arm 42 is fixed to tensionarm pivot shaft 36 for oscillation therewith between a pair ofresiliently mounted contacts 44 and 45. A small universal geared motor46 has an output shaft 47 which drives the speed,

adjustment shaft of the variable transmission unit 20 in one directionor the other to adjust the speed setting of the latter.

The series windings of the motor 46 are indicated schematically in FIG.1 wherein the armature thereof is designated 50 and the forward andreverse field'windings are designated 51 and 52. Winding 51 connectswith contact 44 by means of a conductor 54 and winding 52 connects withcontact 45 by means of a conductor 55. When a contact is closed, thecircuit is from a supply conductor 56 to the contact arm 42, through oneof the conductors 54 or 55 and its associated field winding 51 or 52,through armature-50 and back to a second supply conductor 57.

When the'warp beam drive is on speed and the yarn tension is correct forthe particular setting of adjustable abutment 39 the contact arm willoscillate between the resilient contacts 44 and 45 and engage them forequal time periods, thus energizing the field coils 51 and 52 ofadjusting motor 46 equally in opposite directions during each shortcycle of oscillation of tension shaft 36. These rapidly successiveopposing impulses cancel each other and motor 46 remains stationary.

If the mean position of tension arms 35 moves toward the tight side,that is, if the tension tends to increase, thus calling for an increase,in speed of rotation of the warp beam; to maintain the desired constantwarp feed and constant tension, then the oscillation of the contact armwill be displaced so that it contacts the tight contact 45 for a longerperiod than it contacts the loose contact, during each oscillation.

The preponderance of contact engagement will be accurately proportionateto the degree of deviation of the tension rod 33 and this preponderancewill produce greater torque impulses in field coil 52 than in field coil51. This produces a relatively slow rotation of motor 46, output shaft47, and the speed adjusting shaft of the variable speed transmission 26,to regulate the latter and step up the speed of the warp beam tocompensate for the aforesaid deviation, whatever the reason for suchdeviation may be.

Means are preferably provided for adjusting the distance between thecontacts 44 and 45 to suit various amplitudes of normal oscillation ofthe tension shaft 36 as may be encountered under different knittingconditions. Such means may be as illustrated on a slightly enlargedscale in FIG. 2 wherein the contacts 44 and 45 are pivoted as at 60 and61 and have spring biasing arms 62 and 63 bearing against abutments 64-and 65 to bias the contactstoward each other but permit yieldableoutward movement when the contacts of contact arm 42 bear thereagainst.An adjusting screw 67 has a cam or wedgev formation 68 which projectsbetween the contacts 44 and 45 and determines their minimum spacing tosuit a given set of operating conditions.

Reference will now be had to the embodiment shown schematically in FIG.3 and it is to be understood that this embodiment varies from that ofFIG. 1 only in the electrical means extending from the spaced contactswhich are engaged by the contact arm designated 42 in FIG. 1 which leadultimately to the field coils of the variable transmission adjustingmotor 46. In the two embodiments illustrated in FIGS. 3 and 4 separatetransducer means are utilized between the alternating contacts and theadjusting motor. In FIG. 3 the transducing means comprises a thyratrontrigger circuit and in FIG. 4 the transducing means comprises aswitching reactor control circuit.

In the embodiment of FIG. 3 the conductors from the contactscorresponding to the contacts 44 and 45 of FIG. 1, instead of leadingdirectly to the adjusting motor field windings, trigger an opposed pairof thyratron tubes to produce the desired opposing energization of theadjusting motor field windings in the manner illustrated schematicallyin FIG. 3.

As is well known in the electronic art, in a thyratron tube theformation of an arc and hence the conduction of current from anode tocathode is prevented by the shielding action of the grid when asuflicient negative voltage is impressed on the grid. However, if thegrid voltage is increased from such negative voltage to a less negativevalue or a low positive value, a critical grid'voltage is reached atwhich conduction will start (i. e. anode current starts) and the tube issaid to fire, provided that the anode is positive.

The critical grid voltage at which trigger action begins depends onvarious factors such as the electrode geometry, anode voltage, andsometimes the temperature of the gas in the tube. However, onceconduction starts the grid loses further control and output continues.However, with alternating current voltages conduction ceases during thenegative half of the cycle so that the grid regains control of tubeoutput once during each alternating current cycle.

In FIG. 3 the numerals 144 and 145 designate contacts corresponding tothe loose and tight contacts 44 and 45 of the embodiment of FIG. 1 andare alternately closed in an identical manner to that described in thecase of FIG. 1. The general circuitry of FIG. 3 will be understood bythose skilled in the electronic arts and need not be described indetail.

In this embodiment the adjusting motor armature is designated and thefield windings 151 and 152. The

. gized.

' Contacts 144- and 145 are connected to the grids of thyspcctivcly.

When a given contact 144 or 145 is open the negative grid voltage isgreater than the critical grid voltage and the thyratron is thusprevented from firing. That is, the grid voltage is greater in anegative direct-ion. When one of the contacts closes, the resistors inseries therewith at opposite sides of the grid connection act as voltagedividers and the grid voltage moves instantaneously in a positivedirection and the thyratron fires.

A variable resistor 166 in series with the armature 15% of thecorrection motor serves as a motor speed control to set the rate ofcontrol thereof.

The remaining circuit elements shown in FIG. 3 are largely conventionalin thyr-atron tube circuitry and are briefly as follows:

The resistors 170 through 173 are voltage dividers Whose values areselected so that when the contacts 144 'or 145 close the respective gridbias is such that the thyratron tube fires. The resistors 174 and 175are merely protective grid resistors which limit the grid bias.

The numeral 180 designates a filament supply transformer for thethyratron tubes. The condensers 181 and 182 comprise bypass capacitorsbetween the grids and cathodes of the thyratron tubes to protect againsttransient or surge voltages. The resistors 183 and 190 are isolationresistors and comprise part of the conventional grid bias voltage levelcircuit. Switch 184 is controlled by the main machine driving motor toenergize the control circuitry of FIG. 3 when the machine is started up.The numeral 185 designates a grid bias supply transformer and thenumerals 186 and 187 designate grid bias supply rectifiers. The numeral183 designates a conventional filter capacitor. The numeral 1S9designates a supply voltage transformer.

A still further control arrangement is shown schematieally in FIG. 4 andthis embodiment involves a switching reactor control circuit. FIG. 4shows contacts 244 and 245 which correspond, respectively, to the looseand tight contacts of the preceding embodiments, and forward and reversefield coils 251 and 252 of an adjustment motor likewise corresponding tothat of the preceding embodiment, the armature thereof being designated25s in FIG. 4. It is to be understood that in this as in the precedingembodiments the entire control circuit will be duplicated to control theother warp beam of a conventional knitting machine.

Referring to the field winding 25?. of H6. 4 and the manner in which thesame is energized by closure of the contacts 244, a bridge arrangement27d supplies direct current to two control windings 27d and 277, thearrangement being such that the windings are of opposite polarity.Winding 277 is in series with the tension arm contacts 244. Outputwindings 2% and 281 are arranged to provide full wave rectification andconsequent full wave current to the The reverse field winding 252 isalternately energized and deenergized in a similar manner under thecontrol of contacts 245 throu h a duplicate switching reactor controlarrangement. Control windings 286 and 23-7 correspond, respectively, tocontrol windings 27d and 277, and output windings 29h andiel correspondto the output windings 3% and 281, respectively. As in the precedingembodiment, a variable resistor 266 in series with the motor circuit 2%,251, 252 serves as a speed control for the adjustment motor.

in FIG. 4 the numerals 2%? and 29d designate adiustable current limitingor control resistors and the numerals 7 97 through 3% designaterectifiers which convert the A.C. output of the magnetic amplifier gatewindings to direct current for the motor field coils 251 and 252.

This switching reactor arrangement is particularly advanta eous since itinvolves no moving parts and is virtually impervious to vibration andshock. These features are important from the standpoint of minimummaintenance, long life, and the ability to mount the control directly onthe knitting machine without concern due to the vibration of. themachine.

in certain modern knitting machines the conventional tension arms andpivot shaft arrangements are being replaced by spring plates whichextend the full width of the machine. These plates are secured along oneedge and have a curved surface at the opposite edge for engagementagainst the warp. Thus the flexure of this entire plate provides thespring tension against the warp threads. The control means of thepresent invention in its various forms is equally adaptable to warptension members of this type.

Contacts corresponding to the contact arm 32 may be mounted at oppositefaces of such a spring plate at a point outwardly of its fixed edge tocooperate with spaced tight and loose contacts in the same manner asdecribed above.

I claim:

1. Control apparatus for continuous material being un wound from a reeland passing to intermittent take-up means including resilient meansbearing against said material between said reel and said take-up meansto maintain tension in said material and adapted to oscillate under theintermittent action of said take-up means, a pair of spaced electricalcontacts, and means disposed between said contacts and movable with saidtensioning means, the spacing of said contacts being substantially lessthan the normal amplitude of oscillation 013 said last mentioned meanswhereby the latter engages both of said contacts successively andalternately during each cycle of oscillation of said tensioning means,variable drive means for said reel and a reversible electric motorengaging the same to vary the ratio of said drive means in response torotation of the motor in either direction, said contacts having opposedelectrical connection with said motor whereby the direction andmagnitude of energization of said motor is a substantially continuousresultant of the relative time periods of closure of said pair ofcontacts during each cycle of oscillation of said tensioning means.

2. Control apparatus for continuous material being unwound from a reeland passing to intermittent take-up means including means bearingagainst said material between said reel and said take-up means andadapted to oscillate under the intermittent action or" said take-upmeans, a pair of. spaced electrical contacts, and means disposed betweensaid contacts and movable with said oscillating means, the spacing ofsaid contacts being substantially less than the normal amplitude ofoscillation of said last mentioned means whereby the latter engages bothof said contacts successively and alternately during each cycle ofoscillation of said oscillating means, variable drive means for saidreel and a reversible electric motor engaging the same to vary the ratioof said drive means in response to rotation of the motor in eitherdirection, said contacts having opposed electrical connection with saidmotor whereby the direction and magnitude of energization of said motoris a substantially continuous resultant of the relative time periods ofclosure of said pair of contacts during each cycle of oscillation ofsaid oscillating means.

3. Control apparatus for continuous material being unwound from a reeland passing to intermittent take-up means including variable drive meansfor substantially continuously rotating said reel, resilient meansbearing against said material between said reel and said take-up meansto maintain tension in said material and adapted to oscillate under theintermittent action of said take-up means, a reversible electric motorengaging said variable drive means to vary the ratio thereof in responseto rotation of the motor in either direction, a pair of normally opencircuits for reversely energizing said motor, means comprising a pair ofspaced abutments and means comprising an abutment disposed between thespaced abutments, one of said abutment means being movable with saidtensioning means, the spacing of said spaced abutments beingsubstantially less than the amplitude of oscillation of the movableabutment means whereby the abutment between the spaced abutments engagesboth of said spaced abutments successively and alternately during eachcycle of oscillation of said tensioning means, said pair of normallyopen circuits being adapted to be closed successively and alternately byengagement of each of said spaced abutments with the abutmenttherebetween, at least one of said abutment means being resilientlyyieldable whereby variations in tension of said material which displacesthe center of oscillation of said tensioning means produces unequalabutment time periods with respect to said spaced abutments, saidoscillations being relatively rapid whereby the direction and magnitudeof energization of said motor is a resultant of the relative timeperiods of closure of said two pair of reverse circuits during eachcycle of oscillation of said tensioning means.

4. Control apparatus for continuous material being unwound from a reeland passing to intermittent take-up means including variable drive meansfor substantially continuously rotating said reel, means bearing againstsaid material between said reel and said take-up means and adapted tooscillate under the intermittent action of said take-up means, areversible electric motor engaging said variable drive means to vary theratio thereof in response to rotation of the motor in either direction,a pair of normally open circuits for reversely energizing said motor,means comprising a pair of spaced abutments and means comprising anabutment disposed between the spaced abutments, one of said abutmentmeans being movable with said oscillating means, the spacing of saidspaced abutments being substantially less than the amplitude ofoscillation of the movable abutment means whereby the abutment betweenthe spaced abutments engages both of said spaced abutments successivelyand alternately during each cycle of oscillation of said oscillatingmeans, said pair of normally open circuits being adapted to be closedsuccessively and alternately by engagement of each of said spacedabutments with the abutment therebetween, at least one of said abutmentmeans being resiliently yieldable whereby variations in tension of saidmaterial which displaces the center of oscillation of said oscillatingmeans produces unequal abutment time periods with respect to said spacedabutments, said oscillations being relatively rapid whereby thedirection and magnitude of energization of said motor is a resultant ofthe relative time periods of closure of said pair of reverse circuitsduring each cycle of oscillation of said oscillating means.

5. In combination, reel means and intermittently operating materialengaging means spaced therefrom, said material passing from one of saidmeans to the other, yieldable means bearing against said materialbetween said reel and said engaging means and adapted to oscillate underthe intermittent action of said engaging means, a pair of spacedelectrical contacts, and means disposed between said contacts andmovable with said yieldable oscillating means, the spacing of saidcontacts being substantially less than the normal amplitude ofoscillation of said last mentioned means whereby the latter engages bothof said contacts successively and alternately during each cycle ofoscillation of said yieldable oscillating means, variable drive meansfor said reel and a reversible electric motor engaging the same to varythe ratio of vsaid drive means in response to rotation of the motorvariable drive means for substantially continuously rotating said reel,control apparatus comprising yieldable means bearing against saidmaterial between said reel and said engaging means and adapted tooscillate under the intermittent action of said engaging means, areversible electric motor engaging said variable drive means to vary theratio thereof in response to rotation of the motor in either direction,a pair of normally open circuits for reversely energizing said motor,means comprising a pair of spaced abutments and means comprising anabutment disposed between the spaced abutments, one of said abutmentmeans being movable with said oscillating means, the spacing of. saidspaced abutments being substantially less than the amplitude ofoscillation of the movable-abutment means whereby the abutment betweenthe spaced abutments engages both of said spaced abutments successivelyand alternately during each cycle of oscillation of said yieldabloscillating means, said pair of normally open circuits being adapted tobe closed successively and alternately by engagement of each of saidspaced abutments with the abutment therebetween, at least one of saidabutment means being resiliently yieldable whereby variations in tensionof said material which displaces the center of oscillation of saidyieldable oscillating means produces unequal abutment time periods withrespect to said spaced abutments, said oscillations being relativelyrapid whereby the direction and magnitude of, energization of said motoris a substantially continuous resultant of the relative time periods ofclosure of said two pair of reverse circuits during each cycle ofoscillation of said yieldable oscillating means.

7. Control apparatus for continuous material being unwound from a reeland passing to intermittent take-up means including means bearingagainst said material between said reel and said take-up means andadapted to oscillate under the intermittent action of said take-upmeans, a pair of spaced electrical contacts, and means disposed betweensaid contacts and movable with said oscillating means, the spacing ofsaid contacts being substantially less than the normal amplitude ofoscillation of said last mentioned means whereby the latter engages bothof said contacts successively and alternately during each cycle ofoscillation of said oscillating means, variable drive means for saidreel and a reversible electric motor engaging the same to vary the ratioof said drive means in response to rotation of the motor in eitherdirection, and transducer means acting between said contacts and saidmotor whereby the direction and magnitude of energization of said motoris a substantially continuous resultant of the relative time periods ofclosure of said pair of contacts during each cycle of oscillation ofsaid oscillating means.

8. Control apparatus for continuous material being unwound from a reeland passing to intermittent take-up means including variable drive meansfor substantially continuously rotating said reel, means bearing againstsaid material between said reel and said take-up-means and adapted tooscillate under the intermittent action of said take-up means, areversible electric motor engaging said variable drive means to vary theratio thereof in response to rotation of the motor in either direction,means comprisingta pair of spaced abutments and means comprising anabutment disposed between the spaced abutment-s, one of said abutmentmeans being movable with said oscillating means, the spacing of saidspaced abutments being substantially less than the amplitude ofoscillation of the movable abutment means whereby the abutment betweenthe spaced abutments engages both of said spaced abutments successivelyand alternately during each cycle of oscillation of said oscillatingmeans, a pair of normally open circuits adapted to be closedsuccessively and alternately by engagement of each of said spacedabutments with the abutment therebetween, at least one of said abutmentmeans being resiliently yieldable whereby variations in tension of saidmaterial which displaces the center of oscillation of said oscillatingmeans produces unequal abutment time periods with respect to said spacedabutments and consequent unequal time periods of energization of saidpair of circuits, and

10 transducer means acting between said circuits and said motor wherebythe direction and magnitude of energization of said motor is a resultantof the relative time periods of closure of said pair of circuits duringeach cycle of oscillation of said oscillating means.

References Cited in the file of this patent UNITED STATES PATENTS2,664,724 Lambach et a1 Jan. 5, 1954 2,719,419 Fleckenstein Oct. 4, 19552,720,093 Lambach et al Oct. 11, 1955 2,734,253 Suggs Feb. 14, 1956FOREIGN PATENTS 844,453 Great Britain Aug. 10, 1960

1. CONTROL APPARATUS FOR CONTINUOUS MATERIAL BEING UNWOUND FROM A REELAND PASSING TO INTERMITTENT TAKE-UP MEANS INCLUDING RESILIENT MEANSBEARING AGAINST SAID MATERIAL BETWEEN SAID REEL AND SAID TAKE-UP MEANSTO MAINTAIN TENSION IN SAID MATERIAL AND ADAPTED TO OSCILLATE UNDER THEINTERMITTENT ACTION OF SAID TAKE-UP MEANS, A PAIR OF SPACED ELECTRICALCONTACTS, AND MEANS DISPOSED BETWEEN SAID CONTACTS AND MOVABLE WITH SAIDTENSIONING MEANS, THE SPACING OF SAID CONTACTS BEING SUBSTANTIALLY LESSTHAN THE NORMAL AMPLITUDE OF OSCILLATION OF SAID LAST MENTIONED MEANSWHEREBY THE LATTER ENGAGES BOTH OF SAID CONTACTS SUCCESSIVELY ANDALTERNATELY DURING EACH CYCLE OF OSCILLATION OF SAID TENSIONING MEANS,VARIABLE DRIVE MEANS FOR SAID REEL AND A REVERSIBLE ELECTRIC MOTORENGAGING THE SAME TO VARY THE RATIO OF SAID DRIVE MEANS IN RESPONSE TOROTA-